Piston



Jan. 6( 1925. 1,521,759

H. s. cmDER PTSTON Filed March l, 1924 effectively actuatedtoetfect the seal, by the f tracted'. This results in eliminating a great Patented Jan. 6, 1925. l

UNITED STATES PATENT OFFICE.

HENRY S. CRIDIELR7 OF GENTRALIA, KANSAS.

PIS'ION.

Application filed March 1, 1924. Serial No. 696,258.

the major portion of the sealing area; and a thiner, more pliant andvv hen cient packing can be used;

In the accompanying drawings I Ahave illustrated the i my piston and in these drawings- Figure 1 is a. transverse vertical section throughmy piston and its cylinder;

ig. 2 is a transverse vertical through the cylinder, ton in side elevation; .Y

Fig-."8 is avt-op plan view of the piston without the packing; y

F ig. 4 is a sectional plan view, taken as indicated by the line .1"4 of Fig. 1;

Fig. 5 is a side elevation of the piston without the packing, taken as indicated by the line 5 5 of Fig. 3; and

Fig. 6' is a bottom view of the piston.

To all' whom t may concern:

Be it known that I, HENRY S. CRIDER, a citizen of the United States, and a resident of the city of Centralia, in the county of Nemaha, State of Kansas, have invented new and useful Improvements in Pistons, of which the following is a specification.

This invention relates-generally to pistons for singlel acting cylinders, operated either by hydrostatic or pneumatic pressure, Specifically, itv pertains to a piston of the type wherein a comparatively pliant packing-such as leather or the like-is utilized, and laterally expanded against the cylinder wall, by the pressuregenerated in the compression chamber during the compression stroke, to perfect the seal between the piston and cylinder wall, and which recedes therefrom, to permit loading of the chamsection but showing the pisber, during the.4 suction stroke. In these drawings the numeral l0 desig- I acknowledge that heretofore pisnates a cylinder, which may, ofV course, tons of this general class have been probe additionally fitted with any ofthe wellknown types of inlet and outlet ports, valves, etc., depending upon the use to which it is put.

My piston has been primarily designedl for use in a single acting pum but need not necessarily be limited to tliis type as it will be obvious that it may also be utilized in a double acting umpl and adaptable for pumping any c aracter of fluid pressure;

` The numeral l1 duced, in which an inverted, cup-sliaped, pliant packing has been used, and its peripheral sealing face laterally expanded against the cylinder wall by fluid pressure generated in the compression chamber. But my improvement diiTe-rs from these in that instead of making my packing laterally expansible throughout its entire perimeter, to effect the seal, the major portion of its cylinder engaging surface is normally held in sealing contact with the cylinder wall and only a comparatively small sector of its perimeter made laterally expansible and contractible to effect the seal or permit loading of the compression chamber.

I have found Vby experimentthat. my improvement conduces to a greater. pumping capacity'and more efficient operation of the pumpthan these previous devices, yet possesses all their advantages. Thisis due to the-fact that the smaller, laterally movable sector of the packing is more readilyv and designates rmy pistonv preferably by means of screw-threads -`13.V In its preferred specific form, this piston has a reduced upper its bottom 16, and which forms the bottom of an annular channel between thek piston and cylinder. While the shoulder lmay be right aiigularly disposed, relative to the axis ofthe piston, I preferably make it inclined, relative to this axis, for reasons which I' will later explain.

v The peripheral face 17 of the piston, intermediate the shoulder 15 andthe bottom 16 forms a. comparatively close sliding fit in the internal bore 18 of the cylindervlO, but, ofi course, this t is not airtight;

A flattened side 19 is formed'on the upper reduced portion 14, ofthe piston 11, above the shoulder 15, y width of' this flattened side maybe varied within certain limits to adapt the piston todifferentuses and different weight and types pressure of the compression chamber, or contracted to permit loading, by the vacuum therein, than whenfthe entire ormajor portion of its perimeteris expanded or condeal of ineffective movement of the piston anda consequent' greater pumping capacity. Also, a much better pumpy construction is permitted for the reason that a closer fitting and more effective packing is provided over preferred specific form of centrally mounted upon a piston rod 12,-

end 14 forming an an-v nular shoulder 15, disposed slightlyv above` substantially as shown. The

ce more eii'iof packings; but ordinarily the extent of its area will be relatively small compared with the size of the piston. In determining its size consideration will be given to the thickness of the packing and its circumferential area and the area of the surface 19 then determined to give the most effective from the standpoint of instantaneous actuation, to either expand or contract the sector of ythe packing overlying it at the start of either the compression or suction stroke.

An aperture 20 extends through the piston 11 from 4its bottom face 16 to the flattened face 19 and preferably this aperture will communicate with the latter along its vertical center, as shown in Figs. 3 and 5.

An inverted, cup-shaped, pliant packing 21 is secured over the upper reduced end 14 of the piston 11, so that its free edge 22 will surround this reduced end and fill the space between its periphery and the cylinder bore 18. The packing 21 may be formed of any y suitable material, but preferably it will be 'bore of the by cutting `the made of a pliant leather, formed substantially as shown. In this form it may be rigidly secured in place over the upper end of the piston by means of a nut 23 screwthreadedly mounted on the lower end ofthe piston rod 12. Other ways of securing the packing to the piston may be utilized so long as they are adaptable to securing this type of inverted, substantially cup-shaped packing to the piston, in the manner shown.

The packing 21 will be of such thickness that when confined between the periphery 24, of the reduced end 14, and the bore 18 of the cylinder 10, it will be slightly compressed so as to form a close sealing fit therein entirely around the peripheral face 24, eX- cept over the flattened side 19.

1While in this form of my piston I will depend mainly upon the thickness of the packing 21 to form a close sealing fit in the. cylinder I also take advantage of the pressure generated in the compression chamber C to effect an expansion of the lower peripheral edge 22 of the packing 21, n latter at an acute angle substantially comformable t-o the inclination of the shoulder 14:, as shown in Fig. 1; so that any fluid pressure passing around the lower peripheral face 17 of the piston will pass into the space 25, left between the lower edge ofthe packing 21 and the shoulder 15 to assist in its sealing effect. lVith this type of piston and the use of a packing which will normally have a close sealing fit in the cylinder surrounding `the major portion of the periphery of the piston, this may be small or possibly negligible, buty I provide this means for taking advantage of it if such be possible.

In ythe operation of my piston, the sealing of the fluid pressure in the cylinder is normally effected around the periphery of the results piston, except over the surface 19, by compressing t-.he packing 21 between the peripheral face 2-1 and the cylinder bore 18. The

packing 21 being pliant, during the compression stroke the pressure in the compression chamber C passes through the aperture 2O to the space between the flattened face 19 and the adjacent sector of the packing, forcing the latter outwardlyl into sealing engagement with the cylinder bore. During the suction stroke the vacuum in the compression chamber created by a slight upward movement ofthe piston will immediately draw this sector of the packing 21 extending over the surface. 19 inwardly, permitting fluid pressure to pass this side of the piston and load the compression chamber. As the sector of the packing 21 extending over the flattened surface 19 is comparatively small this will be very readily actuated towards or away from the surface 19 by the vacuum or pressure in the compression chamber C, as the case` may be; and by reason of this quick actuation considerable waste or ineffective movement of the piston in either direction is eliminated. Furthermore, expansion or contraction of this comparatively small sealing area of the packing 21 conduces to a more positive and efficient opening or closing of this fluid pressure passage past the piston.

lhile I have described in this preferred specific form of my improvement the upper reduced end 141 of the piston, the shoulder 15 andrlower peripheral cylinder engaging portion 17, forming when combined with the cylinder 10, an annular channel in which the packing 21 is carried, it is obvious that the broad principlesk of my improvement, which include the pliant packing and flattened surface 19, need not be limited by this preciseconstruction, as the shoulder 15 and enlarged annular portion 17 may be eliminated and the flattened side 19 used in conjunction with a straight cylindrical piston. Other changes may also be made which will ordinarily occur to those skilled in the art. Having described my invention, I claim:

1. A cylindrical piston having a flattened side and a pliant annular packing, carried by said piston, extending over said flattened side.

2. A cylindrical piston having a flattened side and a pliant cup-shaped packing extending over one end of the piston and over said flattened side.

A cylindrical piston having a flattened side and a pliant inverted, cup-shaped packing extending over and secured to one end of the piston so its free edge surrounds the piston and extends over said flattened side.

4. A piston having a reduced end forming a peripheral shoulder thereon, a flattened side on said reduced end, an aperture eX- tending through the piston forming a passage between its botto-1n and said flattened side, and a. pliant packing secured over said reduced end with its free edg'e adjacent said shoulder.

5. A piston having a reduced upper end forming a peripheral shoulder thereon, a flattened side on said reduced end, an ape1- ture extending through the piston forming a. passage between its bottom and said flattened side, and a pliant, inverted cup-shaped packing extending over said reduced end and secured thereto at its top so its free edge surrounds the piston adjacent said shoulder and overlies said flattened side.

6. A piston having a. reduced upper end and a downwardly inclined peripheral shoulder thereon, a flattened side on said reduced end above said shoulder, an aperture extending through said piston forming a passage between its bottom and said flattened side, and a pliant packing secured to the upper end of said reduced portion to extend over said reduced end and flattened side with its free edge adjacent the shoulder, said packing edge being inwardly beveled to conform substantially to the inclination of the shoulder.

7. The combination with a cylinder of a piston having a reduced upper end forming a peripheral shoulder thereon and an annular channel between said end and the cylinder wall, a flattened side on said reduced end above the shoulder, an aperture extending through the piston forming a passage between its bottoni and said flattened side, and |a pliant packing secured in said channel adjacent its top with its free edge adjacent said shoulder and to overlie said attened side.

8. The combination with a cylinder of a piston having a reduced upper end formino' a downwardly inclined peripheral shoulder thereon, an annular channel between said end and the cylinder wall, a flattened side on said reduced end above the shoulder, an aperture extending through the piston forming a passage between its bottom and said flattened side, and a pliant, inverted cup-shaped packing extending over said reduced end and secured to its top, the free edge of said packing extending into said channel to adjacent the shoulder, said edge being inwardly beveled to conform substantially to the inclination of the shoulder.

In witness that I claim the foregoing I have hereunto subscribed my name this 14th day of January 1924.

HENRY s. cRfiDER.A

K. H. GASTON. 

